[PATCH v1 2/5] timer: arm: Introduce functions to get the host cntfrq

From: Andrew Jones <drjones@redhat.com>
To: qemu-devel@nongnu.org, qemu-arm@nongnu.org
Cc: peter.maydell@linaro.org, richard.henderson@linaro.org,
	bijan.mottahedeh@oracle.com, maz@kernel.org
Subject: [PATCH v1 2/5] timer: arm: Introduce functions to get the host cntfrq
Date: Wed, 16 Oct 2019 16:34:07 +0200	[thread overview]
Message-ID: <20191016143410.5023-3-drjones@redhat.com> (raw)
In-Reply-To: <20191016143410.5023-1-drjones@redhat.com>

When acceleration like KVM is in use it's necessary to use the host's
counter frequency when converting ticks to or from time units.

Signed-off-by: Andrew Jones <drjones@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
---
 include/qemu/timer.h | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/include/qemu/timer.h b/include/qemu/timer.h
index 85bc6eb00b21..8941ddea8242 100644
--- a/include/qemu/timer.h
+++ b/include/qemu/timer.h
@@ -1006,6 +1006,22 @@ static inline int64_t cpu_get_host_ticks(void)
 }
 #endif
 
+#if defined(__aarch64__)
+static inline uint32_t cpu_get_host_tick_frequency(void)
+{
+    uint64_t frq;
+    asm volatile("mrs %0, cntfrq_el0" : "=r" (frq));
+    return frq;
+}
+#elif defined(__arm__)
+static inline uint32_t cpu_get_host_tick_frequency(void)
+{
+    uint32_t frq;
+    asm volatile("mrc p15, 0, %0, c14, c0, 0" : "=r" (frq));
+    return frq;
+}
+#endif
+
 #ifdef CONFIG_PROFILER
 static inline int64_t profile_getclock(void)
 {
-- 
2.21.0


